For years, scientists like Hanjoong Jo have been telling us that blood vessels are like rivers and streams. Fluid dynamics are important; the patterns of curvature and current influence where sediment — or atherosclerosis — builds up.
One of the biggest possible perturbations of fluid dynamics in a blood vessel would be to stick a metal tube into it. Of course, cardiologists do this all the time. During percutaneous coronary intervention (PCI), doctors place a stent, basically a metal tube, inside a blood vessel to relieve an obstruction and restore blood flow to the heart muscle.
Habib Samady, Emory Healthcare’s director of interventional cardiology, is leading a clinical trial looking at the effects of stent introduction on blood vessels that are not straight, but curved or angulated. To be eligible for the study, the patient’s blocked vessel has to bend more than 30 degrees. The study will look at patients who have undergone PCI for a heart attack and follow them over the course of a year. Less “disturbed flow†should mean better heart healing for the patient down the road. The study uses OCT (optical coherence tomography) and IVUS (intravascular ultrasound) to monitor the blood vessel and see how healing is affected by fluid dynamics after stent placement.
Now, we want to acknowledge up front that this trial is comparing one FDA-approved stent against another, with the hypothesis that one company’s more flexible stent is going to be better for curved or angulated coronary blood vessels than a less flexible stent. But our focus here is on how this is a clinical test of ideas about fluid dynamics and vascular biology that have mostly been examined in animals so far.
Samady and his colleagues have already examined the relationship between wall shear stress (how hard blood tugs on the side of the blood vessel) and atherosclerosis in human patients. Here, they are investigating fluid dynamics after stent placement.
Studying fluid dynamics involves a lot of computation; Samady says that in his team’s earlier studies, it took months to model each blood vessel. Samady and his collaborators at Georgia Tech have refined and streamlined their methods, allowing them to speed their analysis up considerably.
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